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Phototoxicity of TiO2 nanoparticles to a freshwater benthic amphipod: are benthic systems at risk?
Citation:
Li, S., L. Wallis, H. Ma, AND S. Diamond. Phototoxicity of TiO2 nanoparticles to a freshwater benthic amphipod: are benthic systems at risk? ENVIRONMENTAL SCIENCE AND TECHNOLOGY. John Wiley & Sons, Ltd., Indianapolis, IN, 466:800-808, (2013).
Impact/Purpose:
This study investigated phototoxicity of TiO2 nanoparticles (nano-TiO2) to a freshwater benthic amphipod (Hyalella azteca) using 48-h and 96-h bioassays. Thorough monitoring of particle interactions with exposure media (Lake Superior water, LSW) and the surface of organisms was performed using dynamic light scattering, UV/VIS spectroscopy, and Scanning Electron Microscope. Large agglomeration and sedimentation (>77%) in LSW was observed after 0.5 h. An SSR-favored surface attachment of nanoparticles was observed, indicating enhanced phototoxicity with increased attachment. A 96 h median lethal concentration (LC50) of 29.9 mg/L in H. azteca was calculated, with a daily 4 h UV exposure of 2.2 W/m2. Phototoxicity of nano-TiO2 under SSR had a 21-fold increase as compared to that under ambient laboratory light. This phototoxicity was also dependent on UV dose, with calculated LC50s around 22.9 (95% CI, 20.5 23.3) Wh/m2 when exposed to 20 mg/L nano-TiO2. Also, H. azteca exhibited negative photoaxis in the presence of shelters, indicating that other factors might play a role in environmental systems. Finally, the environmental implications of nano-TiO2 to benthic organisms were illustrated, emphasizing the importance of various environmental factors in the ultimate phototoxicity. This increased phototoxicity and its complex interactions with various environmental factors guarantee further investigations for future risk assessment of photoactive nanomaterials to benthic organisms.
Description:
This study investigated phototoxicity of TiO2 nanoparticles (nano-TiO2) to a freshwater benthic amphipod (Hyalella azteca) using 48-h and 96-h bioassays. Thorough monitoring of particle interactions with exposure media (Lake Superior water, LSW) and the surface of organisms was performed using dynamic light scattering, UV/VIS spectroscopy, and Scanning Electron Microscope. Large agglomeration and sedimentation (>77%) in LSW was observed after 0.5 h. An SSR-favored surface attachment of nanoparticles was observed, indicating enhanced phototoxicity with increased attachment. A 96 h median lethal concentration (LC50) of 29.9 mg/L in H. azteca was calculated, with a daily 4 h UV exposure of 2.2 W/m2. Phototoxicity of nano-TiO2 under SSR had a 21-fold increase as compared to that under ambient laboratory light. This phototoxicity was also dependent on UV dose, with calculated LC50s around 22.9 (95% CI, 20.5 23.3) Wh/m2 when exposed to 20 mg/L nano-TiO2. Also, H. azteca exhibited negative photoaxis in the presence of shelters, indicating that other factors might play a role in environmental systems. Finally, the environmental implications of nano-TiO2 to benthic organisms were illustrated, emphasizing the importance of various environmental factors in the ultimate phototoxicity. This increased phototoxicity and its complex interactions with various environmental factors guarantee further investigations for future risk assessment of photoactive nanomaterials to benthic organisms.
